Section 1: Classifying Matter

Chapter 3: Matter and Energy

Matter or Not?With your partner, decide whether the

items on the card are matter or not matter.

Create a list of properties that apply to all items that you consider to be matter.

Place the cards in the appropriate place on the board once you are finished.

Learning ObjectivesClassify matter as element, compound, or mixture.

Distinguish between heterogeneous and homogeneous mixtures.

Defining MatterMatter: anything that occupies space

and has mass. Some types of matter, such as steel, water,

wood, and plastic, are easily visible to our eyes.

Other types of matter, such as air or microscopic dust, are impossible to see without magnification.

Defining MatterMatter is ultimately

composed of atoms. Atoms: submicroscopic

particles that are the fundamental building blocks of matter.

Defining Matter In many cases, these

atoms are bonded together to form molecules. Molecules: two or more

atoms joined to one another in specific geometric arrangements.

Defining MatterRecent advances in microscopy have allowed us to image the atoms and molecules that compose matter.

Defining Matter Scanning tunneling

microscope image of nickel atoms 

A scanning tunneling microscope (STM) creates an image by scanning a surface with a tip of atomic dimensions.

(Source: Reprint Courtesy of International Business Machines

Corporation, copyright © International Business Machines

Corporation.)

Defining Matter Scanning tunneling

microscope image of a DNA molecule

In this image, the DNA molecule is yellow.

The double-stranded structure of DNA is discernible.

States of MatterThe common states of matter are solid, liquid, and gas. Plasma

Bose Einstein Condensate

States of Matter Water exists as ice (solid), water (liquid), and steam

(gas). In ice, the water molecules are closely spaced and,

although they vibrate, they do not generally move relative to one another.

In liquid water, the water molecules are closely spaced but are free to move around and past each other.

In steam, water molecules are separated by large distances and do not interact significantly with one another.

States of Matter In solid matter, atoms or molecules

pack close to each other in fixed locations. Neighboring atoms or molecules in a solid

may vibrate or oscillate, but they do not move around each other.

Solids have fixed volume and rigid shape.

Examples: Ice, diamond, quartz, and iron

States of MatterCrystalline solid: Atoms or molecules

are arranged in geometric patterns with long-range, repeating order. Examples: salt, diamond

▪ The well-ordered, geometric shapes of salt and diamond crystals reflect the well-ordered geometric arrangement of their atoms.

States of MatterAmorphous solid: Atoms or molecules do not have long-range order. Examples: glass, rubber, and plastic

States of Matter In liquid matter, atoms or molecules are

close to each other but are free to move around and by each other. Liquids have a fixed volume because their

atoms or molecules are in close contact.

Liquids assume the shape of their containers because the atoms or molecules are free to move relative to one another.

Examples: Water, gasoline, alcohol, and mercury

States of Matter In gaseous matter, atoms or molecules are

separated by large distances and are free to move relative to one another. Since the atoms or molecules that compose

gases are not in contact with one another, gases are compressible.

Gases always assume the shape and volume of their containers.

Examples: Oxygen, helium, and carbon dioxide

Concept CheckWhich image best represents matter in the gas state?

Classifying MatterPure substance: composed of only one type of atom or molecule.

Mixture: composed of two or more different types of atoms or molecules combined in variable proportions.

Classifying MatterPure substances include elements and compounds

Classifying MatterElement: A pure substance that cannot

be broken down into simpler substances. No chemical transformation can decompose

an element into simpler substances.

All known elements are listed in the periodic table.

▪ Examples: hydrogen (H), carbon (C), iodine (I)

Classifying Matter Compound: A pure substance composed of two

or more elements in fixed definite proportions. Compounds are more common than pure elements.

Most elements are chemically reactive and combine with other elements to form compounds.

Compounds can be decomposed into simpler substances.

▪ Examples: water, table salt, sugar

Compound or Element?

Molecule/compound

Molecule/compound

Molecule/element Atoms/

element

Classifying MatterPure substances can be represented with a chemical formula. Examples?

Classifying MatterWhen matter contains two types of atoms, it

may be a pure substance or a mixture. A compound is a pure substance composed of

different atoms that are chemically bonded in fixed definite proportions.

A mixture is composed of different substances that are not chemically bonded, but simply mixed together.

Classifying MatterMixtures cannot be represented by a chemical formula. Properties of mixtures can vary since proportions can vary.

Classifying MatterHomogeneous Mixture: a mixture of compounds or elements in which all regions are identical in composition and properties.

Classifying MatterExamples?

Classifying Matter Includes solutions, colloids, and alloys:

▪ Solutions: homogeneous mixtures in which all particles are dissolved. Solutions are usually transparent.

▪ Vinegar, Kool-aid, tea

▪ Colloids: homogeneous mixtures in which larger particles do not separate out from the mixture. Light is usually scattered when passing through.

▪ Milk, paint, smoke

Classifying Matter▪Alloys: a mixture of two metals, or a metal and a non-metal.

▪Can also be heterogeneous!

▪Examples: Brass = copper + zinc

Steel = iron + carbon

Classifying MatterHeterogeneous Mixture: a mixture of compounds or elements in which separate regions are noticeable and have differing compositions and properties.

Classifying MatterExamples?

Classifying Matter Includes suspensions

▪ Suspension: mixture in which particles of one substance is dispersed in the other. These particles can be seen with the naked eye. Particles will settle out of the suspension if left undisturbed.

▪ Examples: sand in water, dust in the air

Concept Check: In the diagram below, which pictures do you think

represent mixtures and which represent pure substances? Explain your answers. (The spheres represent atoms.)

Practice Classify each type of matter as a pure substance

or a mixture. If it is a pure substance, classify it as an element or a compound; if it is a mixture, classify it as homogeneous or heterogeneous. (a) a lead weight

(b) seawater

(c) distilled water

(d) Italian salad dressing

(e) mercury in a thermometer

(f) exhaled air

(g) chicken noodle soup

(h) Sugar